Wednesday, 23 September 2015

Rugby Union vs League. Who’s faster and why?

You may have always wondered which rugby code has the best
athletes. Fanatics of each side will always choose their favoured code of the
two but now we can take a scientific view. While this won’t give the whole
picture as to who are better athletes, we can look into one important facet of performance
being speed. With the NRL finals and the Rugby World Cup currently underway, this
is a good time to compare both rugby codes.

This recent study by Cross et al., (2015) may give some
insight into our question of who’s faster.

NOTE: This data is only a sample of the elite rugby union
and league population.

Who were the
subjects?

15 elite rugby union and 15 elite rugby league athletes were
tested in this study. These were athletes from the New Zealand All Blacks and
the New Zealand Warriors NRL squads respectively. Of the Warriors squad; 7 have represented New Zealand, 5 have represented Tonga, 1 has represented Australia, 1 has represented the Cook Islands and 1 has represented Samoa. Hence both groups of union and league athletes being classed as elite.

What was measured and
how?

Forwards performed 20m sprints while backs performed 30m
sprints. Athlete characteristics (age, height, mass) were recorded between
forwards and backs. Sprinting data was collected through a radar gun system
(similar to a police speed gun). From the radar system, the authors were able
to measure; Vmax (max velocity), v0 (theoretical maximum velocity), vopt
(velocity at peak power production), relative Pmax (peak power relative to body
mass), relative F0 (theoretical maximum force relative to body mass) and
relative Fopt (force at peak power relative to body mass). In
addition to this, split times were able to be measured and were at 2, 5, 10, 20
and 30m splits. Some of these variables are explained in my overshoot
phenomenon series HERE.

The most interesting finding in my opinion is that while
forwards between codes displayed unclear differences in all of the variables
above, they were on average 7.5kg (6.7%) heavier than rugby league forwards. This
means that union forwards are able to
accelerate and reach velocities similar to league forwards while producing
higher amounts of force (ES = 0.77) due to their greater body mass.
Effectively, forwards are able to generate greater momentum (momentum = mass x
velocity) than league forwards essentially giving them greater ability to break
tackles. The authors attributed this difference to the positional demands of
rugby union forwards as they have to overcome a greater number of high force
movements such as scrums, rucks and mauls which favour athletes who can
effectively accelerate their own body mass.

The authors looked further into the acceleration differences
between backs. They determined that the increased acceleration seen by union
backs would mean at 2sec and 4sec of the sprint they would possibly be 0.44m
and 0.73m ahead of their league counterparts respectively. The authors further ascertain
that short sprint performance in elite rugby appears to be related to
horizontal force and power and speculate that acceleration capabilities would
benefit from a more force dominant force/velocity
profile.

Rugby Union wins this
one

Based on the data presented in this study by Cross et al., (2015),
rugby union backs are faster over 30m than their league counterparts. Furthermore,
while there were no differences between forwards in short sprint performance,
union forwards were 6.7% heavier allowing them to possess greater momentum. A
force dominant force/velocity profile seems to be advantageous to short sprint
performance (i.e. being really strong in the horizontal direction). This post
HERE will give you some ideas on exercises to improve short sprint performance.